请教：怎样用下列这段复制对象的代码？

Object.defineProperty(Object.prototype, 'extend', {
  writable: true,
  enumerable: false,
  configurable: true,
  value: function (o) {
    var names = Object.getOwnPropertyNames(o);
    for (var i = 0; i < names.length; i++) {
      if (names[i] in this) continue;
      var desc = Object.getOwnPropertyDescriptor(o, nmaes[i]);
      Object.defineProperty(this, names[i], desc);
    }
  }
}
)
var o={x:1,y:2};
var p={};